1. Field of the Invention
The present invention relates to a use of a stem cell conditioned medium to inhibit oxidation for anti-aging skin. The conditioned medium acquired from WJMSCs conditioned basal medium can effectively scavenge free radicals and increase the survival rate of skin cells under oxidative stress, so that it can improve users undesired skin conditions, e.g. oxidation and aging.
2. Description of Related Art
Nowadays, people become exposed to more intense ultraviolet (UV) radiation than before due to the ozone hole. UV radiation is one of the primary factors contributing to the oxidation of the skin, which causes rapid oxidation and aging of cells. Moreover, the ability to scavenge free radicals is known to gradually decrease with people's ages. If people don't timely care their skin after UV radiation, cell damage will become increasingly severe. Therefore, in order to maintain or restore youthful and flawless appearance, not only females but also males have paid much attention to skin care.
Currently, various natural substances are identified to have antioxidant effects, including vitamin C (L-ascorbic acid), vitamin E, β-carotene, kojic acid, super dismutase and the like. However, some limitations and side effects are existed, e.g. vitamin C is easily oxidized in the sun or in contact with air, cannot withstand high temperature, and may cause skin irritation and redness when the concentration is greater than 5%; and kojic acid is also susceptible to oxidation, leading to discoloration and skin allergy, and may cause cytotoxicity and lesions after a long-term excessive use. Moreover, some antioxidant agents applied on users' skin may directly damage skin cells, which also cause cytotoxicity. Therefore, it is necessary to develop a safer and more effective antioxidant ingredient.
In these years, studies of stem cells have been a growing trend in the world. Stem cells can mainly be divided into two categories, embryonic stem cells and adult stem cells. Mesenchymal stem cells (MSCs) belong to adult stem cells and have a great potential for differentiation. MSCs can differentiate into not only tissues (such as skeleton) derived from mesoderm, but also visceral cells (such as liver and pancreas) derived from endoderm and neurons derived from ectoderm. MSCs are ubiquitous in adults' bodies and can be isolated from bone marrows and various organs. However, the number of MSCs in the bodies is small, and adults' MSCs are known to gradually decrease with the age of the donors. Therefore, how to obtain a sufficient amount of MSCs becomes very important. Bone marrow MSCs are mainly derived from adult bone marrow, but invasive ways to get the bone marrow MSCs may cause pain and discomfort to donors. Umbilical cords contain a number of rich and young MSCs with strong differentiation potential, so they can be used as an important source of mesenchymal stem cells. In comparison with obtaining MSCs from bone marrows, obtaining MSCs from umbilical cords is relatively easy. Moreover, recent studies showed that mesenchymal stem cell-conditioned medium (MSC-CM) can increase the survival rate of dorsal root ganglia cells under oxidative stress of hydrogen peroxide and presents neuroprotective properties (PLoS One. 8(5):e62807, 2013).